Herbivory and drought generate short-term stochasticity and long-term stability in a savanna understory community.

摘要: Rainfall and herbivory are fundamental drivers of grassland plant dynamics, yet few studies have examined long-term interactions between these factors in an experimental setting. Understanding such is important, as rainfall becoming increasingly erratic native wild herbivores being replaced by livestock. Livestock grazing episodic low thought to interact, leading greater community change than either factor alone. We patterns stability herbaceous composition through four dry periods, or droughts, over 15 years the Kenya Long-term Exclosure Experiment (KLEE), which consists six different combinations cattle, (e.g., zebras, gazelles), mega-herbivores (giraffes, elephants). used principal response curves analyze trajectory each herbivore treatment relative a common initial asked how droughts contributed treatments. three measures (resistance, variability, turnover) that correspond temporal scales found had grazing. Treatments included both cattle higher resistance (less net years) but were more variable on shorter time scales; contrast, lightly-grazed treatments (no only) showed lower due accumulation consistent, linear, short-term change. Community was greatest during immediately after all But, while directional less grazed treatments, it variability heavily Much lightly (especially droughts) substantial increases cover palatable grass Brachiaria lachnantha. These results illustrate drought can act together cause communities at moderate end intensity continuum. system with long evolutionary history stability. This runs counter often-held assumptions livestock leads directional, destabilizing shifts systems. This article protected copyright. All rights reserved.